Description:
Improvements of vehicle fuel economy are being considered using a mechanically driven flywheel to reduce the amount of mechanical energy produced by the thermal engine recovering the vehicle kinetic energy during braking. A mechanical system having an overall efficiency over a full regenerative cycle of about 70%, about twice the efficiency of battery-based hybrids, is coupled to a naturally aspirated gasoline engine powering a full size sedan. Results of chassis dynamometer experiments and engine and vehicle simulations are used to evaluate the fuel benefits introducing a kinetic energy recovery system and downsizing of the engine. Preliminary results running the new European driving cycle (NEDC) show KERS may reduce fuel consumption by 25% without downsizing, and 33% with downsizing of the 4 litre engine to 3.3 litres.
Description:
Improvements of vehicle fuel economy are being considered using a mechanically driven flywheel to reduce the amount of mechanical energy produced by the thermal engine recovering the vehicle kinetic energy during braking. A mechanical system having an overall efficiency over a full regenerative cycle of about 70%, about twice the efficiency of battery-based hybrids, is coupled to a naturally aspirated gasoline engine powering a full size sedan. Results of chassis dynamometer experiments and engine and vehicle simulations are used to evaluate the fuel benefits introducing a kinetic energy recovery system and downsizing of the engine. Preliminary results running the new European driving cycle (NEDC) show KERS may reduce fuel consumption by 25% without downsizing, and 33% with downsizing of the 4 litre engine to 3.3 litres.
Description:
Recovery of braking energy during driving cycles is the most effective option to improve fuel economy and reduce green house gas (GHG) emissions. Hybrid electric vehicles suffer the disadvantages of the four efficiency reducing transformations in each regenerative braking cycle. Flywheel kinetic energy recovery systems (KERS) may boost this efficiency up to almost double values of about 70% avoiding all four of the efficiency reducing transformations from one form of energy to another and keeping the vehicle's energy in the same form as when the vehicle starts braking when the vehicle is back up to speed. With reference to the baseline configuration with a 1.6 liters engine and no recovery of kinetic energy, introduction of KERS reduces the fuel usage to 3.16 liters per 100 km, corresponding to 82.4 g of CO2 per km. The 1.6 liters Turbo Direct Injection (TDI) Diesel engine without KERS uses 1.37 MJ per km of fuel energy, reducing with KERS to 1.13 MJ per km. Downsizing the engine to 1.2 liters as permitted by the torque assistance by KERS, the fuel consumption is further reduced to 3.04 liters per 100 km, corresponding to 79.2 g of CO2 per km and 1.09 MJ per km of fuel energy. These CO2 and fuel usage values are 11% and 13% better than those of today’s highest fuel economy hybrid electric vehicle. The car equipped with a 1.6 liter Turbo Direct Injection Jet Ignition (TDI-JI) H2ICE engine finally consumes 8.3 g per km of fuel, corresponding to only 0.99 MJ per km of fuel energy.
Description:
Recovery of braking energy during driving cycles is the most effective option to improve fuel economy and reduce green house gas (GHG) emissions. Hybrid electric vehicles suffer the disadvantages of the four efficiency reducing transformations in each regenerative braking cycle. Flywheel kinetic energy recovery systems (KERS) may boost this efficiency up to almost double values of about 70% avoiding all four of the efficiency reducing transformations from one form of energy to another and keeping the vehicle's energy in the same form as when the vehicle starts braking when the vehicle is back up to speed. With reference to the baseline configuration with a 1.6 liters engine and no recovery of kinetic energy, introduction of KERS reduces the fuel usage to 3.16 liters per 100 km, corresponding to 82.4 g of CO2 per km. The 1.6 liters Turbo Direct Injection (TDI) Diesel engine without KERS uses 1.37 MJ per km of fuel energy, reducing with KERS to 1.13 MJ per km. Downsizing the engine to 1.2 liters as permitted by the torque assistance by KERS, the fuel consumption is further reduced to 3.04 liters per 100 km, corresponding to 79.2 g of CO2 per km and 1.09 MJ per km of fuel energy. These CO2 and fuel usage values are 11% and 13% better than those of today’s highest fuel economy hybrid electric vehicle. The car equipped with a 1.6 liter Turbo Direct Injection Jet Ignition (TDI-JI) H2ICE engine finally consumes 8.3 g per km of fuel, corresponding to only 0.99 MJ per km of fuel energy.
Description:
Downsizing and Turbo Charging (TC) and Direct Injection (DI) may be combined with Variable Valve Actuation (VVA) to better deal with the challenges of fuel economy enhancement. VVA may control the load without throttle; control the valve directly and quickly; optimize combustion, produce large volumetric efficiency. Benefits lower fuel consumption, lower emissions and better performance and fun to drive. The paper presents an engine model of a 1.6 litre TDI VVA engine specifically designed to run pure ethanol, with computed engine maps for brake specific fuel consumption and efficiency. The paper also presents driving cycle results obtained with a vehicle model for a passenger car powered by this engine and a traditional naturally aspirated gasoline engine. Preliminary results of the VVA system coupled with downsizing, turbo charging and Direct Injection permits significant driving cycle fuel economies.
Description:
Downsizing and Turbo Charging (TC) and Direct Injection (DI) may be combined with Variable Valve Actuation (VVA) to better deal with the challenges of fuel economy enhancement. VVA may control the load without throttle; control the valve directly and quickly; optimize combustion, produce large volumetric efficiency. Benefits lower fuel consumption, lower emissions and better performance and fun to drive. The paper presents an engine model of a 1.6 litre TDI VVA engine specifically designed to run pure ethanol, with computed engine maps for brake specific fuel consumption and efficiency. The paper also presents driving cycle results obtained with a vehicle model for a passenger car powered by this engine and a traditional naturally aspirated gasoline engine. Preliminary results of the VVA system coupled with downsizing, turbo charging and Direct Injection permits significant driving cycle fuel economies.
Description:
Current flexi fuel gasoline and ethanol engines have brake efficiencies generally lower than a dedicated gasoline engines because of the constraints to accommodate a variable mixture of the two fuels. Considering ethanol has a few advantages with reference to gasoline, namely the higher octane number and the larger heat of vaporization, the paper explores the potentials of dedicated pure ethanol engines using the most advanced techniques available for gasoline engines, specifically direct injection, turbo charging and variable valve actuation. Computations are performed with state-of-the-art, well validated, engine and vehicle performance simulations packages, generally accepted to produce accurate results targeting major trends in engine developments. The higher compression ratio and the higher boost permitted by ethanol allows larger top brake efficiencies than gasoline, while variable valve actuation produces small penalties in efficiency changing the load. Finally, small, high power density, turbo charged, direct injection, variable valve actuation load controlled engines are proved to operate very efficiently over driving cycles.
Description:
Current flexi fuel gasoline and ethanol engines have brake efficiencies generally lower than a dedicated gasoline engines because of the constraints to accommodate a variable mixture of the two fuels. Considering ethanol has a few advantages with reference to gasoline, namely the higher octane number and the larger heat of vaporization, the paper explores the potentials of dedicated pure ethanol engines using the most advanced techniques available for gasoline engines, specifically direct injection, turbo charging and variable valve actuation. Computations are performed with state-of-the-art, well validated, engine and vehicle performance simulations packages, generally accepted to produce accurate results targeting major trends in engine developments. The higher compression ratio and the higher boost permitted by ethanol allows larger top brake efficiencies than gasoline, while variable valve actuation produces small penalties in efficiency changing the load. Finally, small, high power density, turbo charged, direct injection, variable valve actuation load controlled engines are proved to operate very efficiently over driving cycles.
Description:
Recovery of kinetic energy during driving cycles is the most effective option to improve fuel economy and reduce green house gas (GHG) emissions. Flywheel kinetic energy recovery systems (KERS) may boost this efficiency up to values of about 70%. An engine and vehicle model is developed to simulate the fuel economy of a compact car equipped with a TDI Diesel engine and a KERS. Introduction of KERS reduces the fuel used by the 1.6L TDI engine to 3.16 liters per 100 km, corresponding to 82.4 g of CO2 per km. Downsizing the engine to 1.2 liters as permitted by the torque assistance by KERS, further reduces the fuel consumption to 3.04 liters per 100 km, corresponding to 79.2 g of CO2 per km. These CO2 values are 11% better than those of today’s most fuel efficient hybrid electric vehicle.
Description:
Recovery of kinetic energy during driving cycles is the most effective option to improve fuel economy and reduce green house gas (GHG) emissions. Flywheel kinetic energy recovery systems (KERS) may boost this efficiency up to values of about 70%. An engine and vehicle model is developed to simulate the fuel economy of a compact car equipped with a TDI Diesel engine and a KERS. Introduction of KERS reduces the fuel used by the 1.6L TDI engine to 3.16 liters per 100 km, corresponding to 82.4 g of CO2 per km. Downsizing the engine to 1.2 liters as permitted by the torque assistance by KERS, further reduces the fuel consumption to 3.04 liters per 100 km, corresponding to 79.2 g of CO2 per km. These CO2 values are 11% better than those of today’s most fuel efficient hybrid electric vehicle.